New data from the 1990 U.S. Census released today portray a nation of vast regional differences, fueled in part by a record number of immigrants, who accounted for 37 percent of the country's growth in the 1980s.

More than half the 8.7 million immigrants who entered in the 1980s settled in New York and California, the bureau reported, while many areas were barely touched by the largest movement of people from abroad in the country's history.

The new census data, released in Washington, contain other examples of a country where the national portrait can obscure important regional and local differences.

Median family income nationwide was up a modest 5.5 percent last decade after adjusting for inflation. Yet in New England, median family income was up almost 25 percent, and in the area of Arkansas, Louisiana, Texas and Oklahoma, median family income dropped 4 percent.

More than a quarter of adults age 25 and older in New England had completed college, but in the area of Kentucky, Tennessee, Alabama and Mississippi, a third of adults had not finished high school. The poverty rate rose, from 12.4 percent in 1980 to 13.1 percent in 1990, but it fell from 11.2 to 10.6 percent in the Northeast and rose from 11.3 to 12.6 percent in the West.

"In the past we could just get the national figures and say as a nation we were this, but now the overall picture is really an average of more and more diverse circumstances," said Martha Farnsworth Riche, director of policy studies at the Washington-based Population Reference Bureau. "If community leaders don't recognize this, they'll never be able to manage what will be a more divisive political environment."

The impact of immigration last decade was larger than at any other time this century, according to Jeffrey Passel, a demographer at the Urban Institute in Washington. One of every Americans, or 19.8 million people, is foreign born, according to the census. Of these, 44 percent arrived between 1980 and 1990. "Immigration is still going up," Mr. Passel said. "Legal immigration was expanded by the Immigration Act of 1990, so we're seeing more people coming in as legal immigrants with apparently a continuation of the illegal flow."